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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    <div id="box">hello</div>
    <script>
        const box = document.getElementById('box');

        const tagB = document.createElement('b');
        tagB.append('tag b')

        box.append('hello lili', tagB)

    </script>
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